Liquid Penetrant Testing is one of several methods used in nondestructive testing to locate discontinuities that are open to the surface. Typical applications include the detection of cracks, porosity and "through leaks" leaks that pass from one surface to another

Materials, processes and procedures used in liquid penetrant testing are designed to facilitate capillarity and to make the results of such action visible and capable of interpretation

Because of the basic characteristics of liquid penetrant testing, it is used to test a variety of both metallic and nonmetallic materials such as welds, forging, castings, plastics and ceramics etc. Since liquid penetrant testing is capable of economically revealing surface discontinuities in a variety of dissimilar materials, it is one of the most effective tools available to quality assurance personnel.